in interventional or observational longitudinal studies, the issue of missing values is one of the main concepts that should be investigated. the researcher's main concerns are the impact of missing data on the final results of the study and the appropriate methods that missing values should be handled. regarding the role and the scale of the variable that missing values have been occurred and ...

In a previous paper three types of missing attribute values: lost values, attributeconcept values and “do not care” conditions were compared using six data sets. Since previous experimental results were affected by large variances due to conducting experiments on different versions of a given data set, we conducted new experiments, using the same pattern of missing attribute values for all thre...

Recently, results on a comparison of seven successful methods of handling missing attribute values were reported. This paper describes experimental results on the three most successful methods out of these seven. Two of these methods, based on a Closet Fit idea (searching in a remaining data set for the closest fit case and replacing a missing attribute value by the corresponding known value fr...

BACKGROUND Dental anomalies associated with different severities of cleft lip and palate have been rarely reported. This retrospective study investigates the characteristics of dental anomalies associated with different types of cleft, and compares the dental anomaly traits based on sex and severity of cleft. METHODS Cleft patients born in 1995 with qualified diagnostic records from 7 to 11 y...

OBJECTIVE To document the perceived frequency, type, and impact of unavailable ("missing") clinical information during pediatric emergency and general ambulatory encounters. METHODS This prospective cohort set in the Emergency Department and General Ambulatory Pediatric Clinic at The Children's Hospital, Aurora, CO, assessed pediatric attending physician perceptions regarding missing informat...

Atom Probe Tomography (APT) combines atomic imaging with a time-of-flight mass spectrometer to provide direct space three-dimensional, atomic-scale resolution images of materials with the chemical identities of all the detected atoms. Quantitative analysis of APT data through advanced data mining methods enhances the chemical characterization of alloy systems and accounts for the statistical un...

density functional (dft) calculations at m05-2x/aug-cc-pvdz level were used to analyze the interactions between dimethyl sulfoxide (dmso) dimers. the structures obtained have been analyzed with the atoms in molecules (aims) and natural bond orbital (nbo) methodologies. four minima were located on the potential energy surface of the dimers. three types of interactions are observed, ch•••o, ch•••...

Data plays a vital role as a source of information to organizations, especially in times of information and technology. One encounters a not-so-perfect database from which data is missing, and the results obtained from such a database may provide biased or misleading solutions. Therefore, imputing missing data to a database has been regarded as one of the major steps in data mining. The present...

Ž . ABSTRACT: Bond-charge increments BCIs are additive parameters used to assign atomic charges for the MMFF force field. BCI parameters are classified parsimoniously according to two atom types and the bond order. We show how BCIs may be fitted rapidly by linear least squares to the calculated ab initio Ž . electrostatic potential ESP or to the electrostatic field. When applied simultaneously ...

Surfactant-stabilized metal nanoparticles have shown promise as catalysts although specific surface features and their influence on catalytic performance have not been well understood. We quantify the thermodynamic stability, the facet composition of the surface, and distinct atom types that affect rates of atom leaching for a series of twenty near-spherical Pd nanoparticles of 1.8 to 3.1 nm si...